OP MICROSCOPIC OBJECTS. 17$ 



mouth of the animal, and an incision made directly back- 

 wards in the middle line above to some distance behind the 

 tentacles ; the tongue is then immediately brought into view, 

 lying along the floor of the mouth." 



Dr. Alcock's method of dissection will be found to differ 

 in some degree from the general rules before given; and 

 when the tongue is dissected out he washes it for one hour 

 (shaking it now and then) in a weak solution of potash. 

 After cleaning thoroughly in water, it must be mounted by 

 one of the methods before mentioned. 



Mr. Edwards, of New York, no mean authority, gives his 

 experience as follows : I use a rather strong solution of 

 caustic potassa, the strength of which I cannot specify as it 

 must differ with the species under manipulation, as some 

 ribbons (or tongues) are injured much sooner than others.. 

 Plunge the whole animal in this solution; in the case of 

 very small creatures shell and all. I have found it better 

 to let the animal stand until it dies and begins to decom- 

 pose, when it can readily be removed and falls in pieces. 

 The lingual ribbon is not so easily decomposed. Now place 

 and leave the animal in the potassa solution for some days, 

 or boil at once. Almost everything is now dissolved but 

 the shell, some few fragments, and the desired! r'bN?n. 

 Wash carefully with fresh water, and if it is to be preserved 

 before mounting, remove to alcohol. To mount it, remove 

 from the spirit and boil a short time in turpentine, when it 

 can be put up in Canada balsam. Mr. May expresses him- 

 self as " standing utterly aghast " at any man so interfering 

 with nature as to put up these objects in balsam, thus 

 pressing and destroying their true forms. - He recommends 

 a cell and a weak form of Goadby's solution. 



Amongst insects, especially the grasshopper tribe, are- 

 found many which possess a gizzard, armed with strong 

 teeth, somewhat similar to those of the molluscs. It 

 requires great nicety of manipulation to obtain these for the 

 microscope; but Mr. L. G-. Mills, before quoted, gives the 

 following instructions : Kill the insect with chloroform and 



